Means for cleaning the plates of an electrostatic air or gas cleaner



May 8, 1934. R. c. THOMPSON 1,957,560

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Patented May 8, 1934 MEANS FOR CLEANING THE PLATES OF AN ELECTROSTATIC AIR 0R GAS CLEANER Richard C. Thompson, Woodmont, Conn.

Application May 16, 1931, Serial No. 537,908

43 Claims. (Cl. 183--7) In my application Serial No. 523,451, filed March 18, 1931, I have shown and described a special design of electrostatic precipitator; i. e., an apparatus for removing particulate matter from a stream of air or any other gas.

Since the principles broadly underlying my scheme for cleaning such a gaseous stream are shown, described and claimed in the aboveidentified application, I shall not go into the detail of the principles involved in my present application more than is needed to make the same understandable, as the present application is directed to means for automatically removing the accumulated particulate matter collected by the precipitator of said pending application.

aforementioned pending application, works on the principle of pure electrostatic attraction as distinguished from those devices which work on the more or less dynamic principle of ionic bombardment. In .both devices, the electrodes, which are the collecting surfaces, are preferably of metal sheets coated with, some fibrous material, such as burlap, on which an electric charge is maintained from some suitable source of potential; These electrodes, or plates as I term them, are arranged in parallel spaced relationship, and the stream of gas to be cleaned passes between them. The solid matter contained in the said stream of gas is attracted to. the surfaces of the plates, and there, as I have set forth in my prior application, it is held due to the nature of the said surfaces. Obviously, after a time, the accumulated material must be removed, and this application is directed to means for so doing without sacrificing the advantages of the unitary construction described and claimed in the above-mentioned pending application. The unitary construction, as I term it, consists of assembling the plates in small self-contained groups or units, each unit being preferably identical with the others, and each unit so designed that it will fit adjacent any other unit so that a complete machine of any size or shape within reasonable limits may be built up by simply assembling the proper number of units together. This assembling should be simple enough so that it may be done in the field by ordinarily good mechanicswithout any special training.

The main object, therefore, of this invention is to provide a self-cleaning electrostatic precipitator primarily for ventilation purposes which may be built in a wide variety of shapes and sizes at moderate cost. Other and ancillary objects will be discerned by one skilled in the art upon study of the specification and annexed drawings wherein:

Figure 1 is a perspective view of one of the completely assembled units of plates, without the cleaning nozzles, which may be utilized by itself or combined with similar units to form a larger machine.

Figure 2 is a. fragmentary perspective view of one of the plates showing the method of making electrical contact thereto, as well as other details.

Figure 3 is a fragmentary perspective view showing how two units of Figure 1 may be combined.

Figure 4 is a part-side and sectional elevation of the apparatus with the vacuum tube or pipe line cut away, and with the cleaning nozzle operating mechanism in downward position about to start upward movement of the cleaning nozzles.

Figure 5 is a view similar to Figure 4, but with the side panel cut away showing the cleaning plates and packing material which assists in forming a common suction chamber inside the panel and insulates the side section from the last plate. In this view, the nozzle operating mechanism is in the upposition about to be drawn downwar'dly. v I

Figure 6 is a combination view of Figures 4 and 5, showing the nozzle operating mechanism in up position, the end panel being broken away to show one of the nozzles inengagement with the operating arms.

. Figure 7 is a section on the line 7-7 of Figure 8, showing three of the units as illustrated in Figure 1, with the cleaning nozzles in their downposition.

Figure 8 is a front elevation of-the machine shown in'Figures 4 to 7 inclusive, taken at one end of the machine, with the other end broken away beyond the first unit.

Figure 9 is a sectional view taken at one side of the machine within the end panel, showing the-method of joinder of the different sections, and also illustrating the space provided for the nozzle curtains which maintain a vacuum below the nozzles while they are-being operated.

Figure 10 is a skeleton view of Figure8 show- .ing, progressively from the bottom of the sheet up, the manner of joining the different sectional units.

Figure 11 is a fragmentary view of one corner of the upper unit showing certain details of the construction.

Figure 12 is a fragmentary sectional view on the line'1212 of Figure 13 of the upper part of the machine, illustrating the method of making electrical contact with the plate studs.

Figure 13 is a fragmentary sectional view on the line 13-13 of Figure 12.

Figure 14 is a sectional view on the line 14-14 of Figure 12.

Figure 15 is a detailed view showing the method of making electrical contact between the contact terminal strip and the plate studs, as well as the means for connecting the electrical contact strips of the different sections together.

Figure 16 is a part plan and sectional view looking down on the cleaning nozzles which are positioned between adjacent plates having surfaces to be cleaned.

Figure 17 is a side view, partly in elevation and partly in section, of a modified form of cleaning nozzle.

Figure 18 is a fragmentary section of a further modified form of nozzle.

Figure 19 is a fragmentary view, .partly in section and partly in elevation, of a self-aligning device which may be used with the cleaning nozzle to shut off the vacuum when the nozzle is in its normal inoperative position.

Figure 20 isa fragmentary view looking at the ends of the plates, showing a section through one of the cleaning nozzles illustrating the pas sage of air through the nozzle.

Figure 21 shows a part of the nozzle mechanism in different positions of its cycle of operation.

Figure 22 is a schematic view showing the progressive movement of the cleaning nozzle operating mechanism.

Figures 23 and 24 are further schematic views which are to be considered in connection with Figure 22.

Figure 25 is a modified form of cleaning nozzle and actuating arm.

Figure 26 is a perspective view of one form of gas cleaning apparatus, utilizing a number (9 being illustrated) of individual units as shown in Figure 1. This figure also shows one end of the duct for bringing the air or gas to the cleaning apparatus. v

Figure 27 is a view of part of the gearing mechanism for operating the cleaning nozzles.

Figure 28 is a view looking from the bottom of Figure 27.

Figure 29 is a perspective view of the bracket for supporting part of the gearing.

Referring now to the details wherein like numbers refer to corresponding parts in the various views, it may be said in general that a complete machine consists of four different kinds of parts; namely, units; end sections, top sections, cleaner mechanism, and base sections. To these parts of the precipitator proper, are to be added various auxiliary machines such as the rectifier for supplying the proper kind of current, and the exhauster to furnish the vacuum for the cleaning devices. As set forth above, by varying the number and arrangement of these basic parts, a precipitator of any desired capacity or proportion may be built up.

Figure 1 shows one of the basic units. It will be seen to consist of a number of plates, preferably of metal coated with fibrous material, and a frame consisting of bottom rails 2 and 3, which are preferably identical, spacer member 6, and top sheet 4, all of which must be made of insulating material. In member 6, is a hollow chamber 8 which extends from end to end of the member, the purpose of which will be described below. Communicating between this chamber and the spaces between the plates, are a series of holes 9. These holes may be round, as shown, or they may be long slots, or any other desired shape. At each end of the member 6, is a hole 10 which matches with holes in the plates, so rods 11 may be run through to hold the plates in position once they are set in slots 7. If a number of units are set side by side, these 'rods may run through all the groups and thereby anchor the groups firmly together. It is obvious that when this is done,-the chamber 6 in each unit will communicate with the corresponding chamber in the adjacent unit, in effect forming a single chamber for the entire horizontal row.

The plates themselves are equipped with pins 12 at the top. These pins may be on alternate front and back ends as shown in Figure 1, or they may be on both ends. They are equipped with slots 13 on either end. One of these slots is passed over the plate, and the pin is preferably spot-welded in place. They project through suitable holes in -the top sheet 4. On the bottom the plates are preferably slotted at 14, these slots being so arranged that they are directly below the pins 12. Members 2 and 3 have suitable holes in them, so that when a unit is placed ontop of another the pins will project through these holes and engage the plates at the slot 14 just as shown in Figure 3. Thus it may be seen that any number of these units may be piled one on top of the other, and that they will be locked in place by the pins 12, and these same pins will also serve to electrically connect all the plates in one vertical row. The one other part of the basic units are the channels 28 which are mounted on either side of the plates 1 and both edges, thus making four per plate. The channel proper matches with the space formed between the outside of member 6 and the inside of members 2 and 3; it serves as a guide for curtains, the purpose of which will be later explained.

Figure 9 shows very clearly the effect of piling units one on top of each other. Note particularly the chamber formed by the space beneath member 6 of an upper unit and member 4 of one beneath. This space serves to stow the curtains mentioned above, out of the way when they serve to stiffen the structure, and to provide a means of fastening adjacent top members together. This is accomplished by bolting them through holes 101. Holes 100 on the other two angles serve for bolts to hold the ducts carrying air to and from the precipitator. flanges of the channel are mounted guides 70 and 102 for the cleaner drive mechanism, as will be described below.

To the inside of the channel 17 are attached insulating blocks 18 and 19 which keep the metal of the section from short-circuiting the plates and at the same time carry the busses that supply the plates with potential. These blocks are shown in detail in Figures 12, 13, and 14. As will be seen in these drawings, they are drilled with holes that match over pins 12 of the top unit. Along one side of them is mounted bus bar 20 and from this bus towards alternate holes, but somewhat oiT center, are drilled another set of holes. In these holes are set small springs 22 which touch the bus bar on one end and engage the pins 12 on one side near the other end. Bus bars of adjoining sections overlap as shown in Figure 15. Thus, if an electric potential is applied to one of these bars, this potential is communi- To the e cated to alternate plates on the unit directly below the top section, and from that unit to the units below, as explained above. The block on the opposite side is similarly connected to the remaining plates,and so, if the potential of opposite polarity is applied to this bus, it charges the latter plates to the polarity of this bus. Thus we can see that the whole machine is charged by simply connecting up to these two busses, no matter how large this machine may be.

The side or end sections, which will now be briefly described, serve'several purposes. They connect all the chambers 6 of the several units together; they seal off the last plate of the outside units, and they provide a place to connect the sides of the ducts delivering the air to, and receiving theair from the machine, the incoming air-duct being shown in Figure 26 by the numeral 104. They also carry the connection 32 to which the exhauster is attached that draws the vacuum for cleaning the plates. The construction of this section is clear enough in the drawings so that no further detailed description is needed.

The base sections serve to mount the units. They are equipped with a top plate 103 of insulating material which serves the bottom unit, just as the plate 4 of that unit serves the unit above. It also carries the guide rail for the cleaner drive mechanism, and in general acts as a foundation for the whole machine. Like the top sections, they are preferably built in units of the same length as the cleaning units.

The cleaning mechanism consists of the cleaner nozzles which are mounted between each pair of plates; the exhauster, and the drive mechanism. The nozzles shown herein are separately disclosed and claimed in my application S. N. 527,183, filed April 2, 1931, and therefore need not be described in detail here. The nozzle is shown in Figures 16, 1'7, 18, 19, and 20. A mod-' iiication of it is shown in Figure 25. It consists of two riding members 35 and 36, and a main central portion 29. The riding members extend only over the part of the plate to be cleaned, but the central portion extends out beyond the units and is provided with slots '75 which are engaged by members of the cleaner drive mechanism. On each end of the nozzle is a curtain 30 which, when the nozzles are in place, slide in the channels 28, sealing oil. the space below the cleaners when they are lifted up above the bottom plates of the-units, for a reason to be presently described. On the bottom of the units, as indicated in Figure 19, may be set small buttons 39 loosely supported by pins41 having collars 42. These buttons are so locatedthat they act as valves to seal up holes 9 in the bottom spacers 6 when the nozzles are at the bottom of their travel. Another method of sealing these holes ls shown in Figure 18, in which a soft pad 38, such as sponge rubber, is attached to the bottom of the nozzles. Other ways may be devised, and I do not limit myself to those shown. Referring to Figures 16, 18, 19, and 20, in Figure 20 we see a nozzle in cross-section as it would be while cleaning is taking place. It may be noted here that these nozzles must be made of good insulating material in order not to shortcircuit the plates. A partial vacuum is drawn below the nozzle in a manner described later, which causes the air to rush from above the nozzle (as indicated by the arrows, Fig. 20) splitting on member 34 and flowing with increasing velocity through slots 37 between members 35 and 36 and member 34. The jet of air thus formed impinges on the surface of the plate, picking up the dust and rebounding back into the chamber formed under the nozzle, which chamber is bounded on the sides by the plates;

on the top by the nozzle, and on the bottom by the spacer member 6. From here, the air with its load of dirt is drawn through holes 9, as described below.

The associated mechanism works as follows:

The cleaning action of the nozzles may be now considered, assuming that a machine is all assembled and ready to run, except that the charging current is switched off. All the cleaner nozzles are in their normal position; namely, at the bottom-of their travel, and the curtains associated with them are stowed in chamber 31 between the members 6 and 4. If a vacuum is started on connection 32 on the side section, it will exhaust the air out of chamber 8 under all the units, as they are all inter-connected; but the only place for the air to get in, is through holes 9 between the plates, and these are all closed oil by whatever device we have put on the bottom of the nozzles. Let any one of these nozzles be raised. As soon as it is lifted off its seat, it opens the holes under it, and the air rushes down through the nozzle-it cannot come between the plates under the nozzle, because the act of raising the nozzle has lifted the curtains 30 associated with it, which, riding in channels 28, seal off this path. Thus we can see that the whole capacity of the exhauster is exerted on this one nozzle. As the nozzle is lifted to the top of its travel and lowered again until it seats, the facing surfaces of one pair of adjacent plates have been cleaned. If another nozzle is likewise operated, then another, and so on, until every one in the whole machine has been operated, every plate in the machine will have been cleaned on both sides; but at no time has more than a single nozzle in any one unit been in action, and the exhauster therefore need only be large enough to draw enough air to operate a single nozzle.

The purpose of the cleaner drive mechanism is to do just what has been described; i. e., to lift a single nozzle of each unit, or a small number of nozzles, namely those in the same vertical row, off their seats, up to the top of their travel, and then set them down again on their seats, and then proceed to the next nozzle or group of nozzles, and so on until the whole machine is cleaned. Furthermore, it is the purpose to do this automatically and without supervision. To accomplish this action, the following operating mechanism is provided.

This operating mechanism produces a double motion, shown diagrammatically in Figures 22, 23, and 24; a reciprocating up-and-down motion combined with a side-wise progression, the members which actually operate the cleaner nozzles only making their side-wise motion at the bottom of the stroke when they are not engaged in the nozzles. This motion is produced by identical mechanisms on the front and back of the machine, so each set of cleaner nozzles in a vertical direction is picked up in its turn, raised to the top of the unit in which it is set, then returned to the bottom of its unit, after which the mecha- I on each of which slides a small worm gear 98 that drives gear 99, which in turn drives, through a suitable shaft 96, the skew gear 66and crank arm (see Figs. 27 and 28). The crank arm 65, operating through-connecting rod 64 and'pin 56 held crosshead 5'7 (Fig. ,8), produces the necessary reciprocating motion. Skew gear 66 drivesgear 47 which is fastened to. shaft 51 that, acting through pinion 67 and rack68 at the bottom, and pinion 69 and rack 70 at the top, produces thesidewise motion. This sidewise motion, through the various members of the framework supporting these gears, is communicated to the entire assembly. Rotatably mounted on shaft 51, is sleeve 50 to which the reciprocating motion of pin 56 as described above, is communicated by collar 55 set between clamping collars 53 and 54 held in position by clamp screws 52. Thus it will be seen that sleeve 50 gets a combination of the up-and-down reciprocating motion and the steady sidewise progression; but, nevertheless, it is free to rotate about its own axis while going through this combination motion. Firmly clamped to this sleeve, are yokes or arms 71, one for each vertical section or unit. These yokes or arms have forks 72 and 73, and on the inside of the forks 72 and 73, are set pins 74 which engage in the elongated slots 75 in the ends of the cleaner nozzles. At the bottom of sleeve 50, is cam 49 which engages in a slot '76 in the hub of gear47, when said sleeve is at the bottom of its travel.

As mentioned above, the mechanisms on the front and back of the machine are identical, so the description applies equally to either mechanism.

Coming now to the general operation of my automatic cleaning machine, it is assumed that the parts are substantially in the position shown in Figures 4 and 7, wherein the nozzles 29 are in their normal inoperative position and the arms 71 are in about the position as shown. However, in Figure 4, the upward movement of the arms 71 has begun and the cam 49 is out of its cooperating slot 76 in the hub 48 of the gear 47. The pin 74 in the fork 73, engages the slot 75 at the end of the nozzle 29, the operation being the same on the opposite side of the machine, and the pinion 66, operaiing through the gear arm 65 and connecting rod 64 and through the other associated parts, carries the sleeve 50, with all of the arms 71 carried thereby, upward, starting each cleaning nozzle 29 on its cleaning stroke.

As the arms 71 continue on their upward stroke, the entire shaft 51, with all the parts is moved laterally along the side of the machine by means of the rack and pinions 6768, 69-70, and this movement means that the sleeve 50 must turn with the collars 53 and 55, and likewise the arms 71 must swing through an angle. This compound movement is depicted in Figures 22, 23, and 24, wherein it is seen, by reference to Figure 22, that at the point 77, the arm 71 is just beginning its upward travel. When it reaches the point 78, the arm 71 is then half-way between two adjacent plates and parallel with the plane of the plates, and in the position as shown in Figure 6.

'The return movement is then started by the crank arms 65, and the point 79' illustrates the position where the pin 74 in the fork '72 engages the slot 75 in the nozzle and is ready to move the same on its downward stroke, the path of movement on the up stroke being indicated by the broken line 80, and the downstroke by the broken line 81.

When the arm 71 reaches the position 82, the

nozzle is in its lowermost position, shown in Figure 7, and the cam 49 on the sleeve 50 has entered its cooperating slot '76 in the hub 48 of the gear 4'7. As soon as the crank arm 65 passes the central downward position, the arm '71 starts 80 upwardly, releasing the pin 74 in the fork 72 from the slot 75 in the nozzle, thereby allowing the arm 71 with the sleeve 50 to turn in response to the action of the cam 49 in its cooperating slot 76. The cam is so constructed that thisaction is such that the arm 71 is swung quickly through the angle 83, due to the combination of the rotation of the hub and the pitch of the side of the slot (see Figures 21 and 24), so that the pin 74 in thefork 73 is ready to engage the slot 75 in the end of the nozzle positioned between the next succeeding pair of plates, and the arm is then in the position 77 before starting upwardly again on another cleaning cycle between a succeeding pair of plates. This operation is continuous as the shafts 51 on opposite sides of the machine travel back and forth in front of the spaces between the plates.

After the plates have been cleaned in the manner set forth, the motor 44 is stopped when the nozzles have reached the position indicated in Figure 7, and the precipitator is then ready to have the charging current switched on and the air or gas forced through the plates. When it is to be cleaned again, the motor is started in reverse direction.

It is to be understood that the cleaning apparatus operates automatically by merely switching off the exciting current of the precipitator and switching on the cleaning motor together with the vacuum line, and the operation of cleaning takes but a few minutes time whereby the cleaning may be done during an interval when clean air or gas is not required. Automatic switches, operated at predetermined intervals by various wellknown devices, may be adapted to relieve even the labor of working the switches.

In Figure 25, the arm 71 is hollow and likewise the forks 72 and 73, each being equipped with a valve 84 normally held by spring 85 against a seat 86, but adapted to be unseated by pin 89 which is attached to valve 88 in the end of the cleaner nozzle. When the valve 88 is in the position shown in Figure 25, it closes a conicallyshaped hole 87 in the nozzle, which fits the seat 95 on the arm 73, when the member 71 is moving in the opposite direction from that shown in Figure 25 when the nozzle is in engagement with the conically-shaped part 93 of fork '72.

The outlet 94 is connected to the source of vacuum by some suitable means such as a flexible hose. The come-and-go, due to the rotation of the arm about shaft 51, is taken up by the sliding joint 90 in the end of the cleaner arm 29, which in this case is formed differently than shown in Figure 16. This scheme eliminates the need of the chambers 8 and 31 in the cleaner assembly. The cleaner itself does not differ materially from that in the other design, and the operating mechanism is identical. It will be seen from this drawing that when the cleaner is being pushed down by the forked arm, the air is drawn out of the cleaner nozzle through the upper arm 72 of the fork; similarly, when the nozzle is being pushed up, the air is drawn out through the lower arm 73 of the fork. While the arm is in transit between nozzles, both valves 84 are closed and no air gets through.

From what has been said, it will be clear that many changes may be made in the details of this 150 invention without materially changing the scheme by which it works, and I therefore do not wishto be unduly limited in the interpretation of the appended claims.

Having thus described my invention, what I claim is:

1. In an air or gas cleaner of the type herein specified wherein a group of spaced parallel plates are provided with surfaces which hold the particulate matter thereon when attracted thereto by electrical charges applied to said plates; apparatus for cleaning said plates including a plurality of members positioned to form a chamber extending adjacent one edge of the plates and at right angles to the plane of the plates, means for applying suction to said chamber, said chamher having openings into the several spaces between said plates, a cleaning nozzle between each pair of plates and normally positioned so as to cover the said openings from the suction cham-' ber, means for moving at least one of said nozzles at a time so its opposite suction edges simultaneously pass over the surfaces of the plates between which it is positioned, and means for closing off, on the suction side of the nozzle, the air or gas intake and discharge openings between the plates where and as the nozzle is being moved.

2. A mechanism according to claim 1, in which the said closing-off means comprises flexible stips carried by each end of the nozzle,means being provided to receive said strips when the nozzle is in non-working position.

3. A mechanism according to claim 1, in which the said closing-off means comprises flexible strips attached to opposite ends of the nozzle, and further, in that guide members for the nozzle and strips are provided along the edges of opposite sides of each plate.

4. A mechanism according to'claim 1, in which each of the nozzles is provided with special seat members to close off the said openings from the suction chamber.

5. A mechanism according to claim 1, in which each of the nozzles is provided with self-aligning seat members to close off the said openings from the suction chamber.

6. A mechanism according to claim 1, in which the means for moving the nozzle comprises a pair of movable members on opposite sides of the machine, and an arm carried on each member, the arms engaging opposite ends of the nozzle with means for actuating said movable members.

7. In an air or gas cleaner of the type herein specified wherein a group of spaced parallel plates are provided with surfaces which hold the particulate matter thereon when attracted thereto by electrical charges applied to said plates; apparatus for cleaning said plates inclding aplurality of members positioned to form a chamber extending adjacent one edge of the plates and at right angles to the plane of the plates, means for applying suction to said chamber, said chamber having openings into the several spaces between said plates, a cleaning nozzle between each pair of plates and normally positioned so as to cover the said openings from the suction chamber, shafts vertically positioned adjacent opposite sides of the group of plates, a sleeve on each shaft, a forked arm carried on each sleeve and adapted to engage opposite ends of each nozzle, means for rotating said shafts, means for causing said shafts to move in front of said plates across the open ings therebetween, means for oscillating said sleeves, and means for automatically transferring said arms from one nozzle to an adjacent one on completion of a full cycle of movement of the nozzle engaged by said arms.

8. A mechanism according to claim 7, in which a plurality pf units of said groups of plates similarly arranged, are assembled one above the other, and each assembled group is provided with its cleaning nozzle, while said shafts and sleeves are extended and equipped with a forked arm for each group of plates.

9. A mechanism according to claim 7, in which a plurality of units of said groups of plates are arranged transversely and vertically, said pair of shafts serving all units, but their length and that of the sleeves and number of forked arms being dependent on the number of units arranged in vertical rows.

10. In an air or gas cleaner of the type herein specified wherein a group of spaced parallel imperforate plates are provided with surfaces which hold the particulate matter thereon when attracted thereto by electrical charges applied'to said plates; means for cleaning said plate surfaces including a nozzle between a pair of plates and adapted to engage both plate'surfaces simultaneously and normally positioned at the bottom of the spaces between the plates, means for raising and lowering said nozzle, and means for applying suction to the nozzle, and means for causing air currents to pass through the nozzle and against the surfaces to be cleaned as it is moved.

11. A mechanism as set forth in claim 10, in which means are provided for automatically raising and lowering successively all of said nozzles normally positioned in the same vertical plane.

12. In an air or gas cleaner of the type herein specified wherein groups of spaced imperforate plates, impervious to the passage of air or gas, are provided with surfaces which hold the particulate matter thereon after being attracted thereto by electrical charges applied to said plates; means for cleaning simultaneously at least two of said oppositely disposed surfaces, said means including; an extendednozzle normally closing a suction passageway leading into the spaces between said two plates and extending clear across the plates, means for moving said nozzle, and means for maintaining the suction passage below the nozzle as it is moved.

13. A mechanism as set forth in claim 10, in which each nozzle carries a flexible curtain at each end for preserving a vacuum passageway below the nozzle as the nozzle'is raised and lowered.

14. A mechanism as set forth in claim 12, in which means are provided for automatically raising and lowering simultaneously all the nozzles in diflerent groups, but in the same vertical plane, and successively moving those nozzles in adjacent spaces in the different groups. 1

15. A mechanism as set forth in claim 12, in which a single mechanism is provided for moving simul t aneously all the nozzles in the same vertical plane or plate spaces and then progressively and automatically moving all the nozzles in the successive spaces between plates.

16. A mechanism as set forth in claim'12, in which the means for moving the nozzle or nozzles includes shafts positioned on opposite sides of the plates and mounted to be moved transversely across the spaces between the plates, arms carried on said shafts for engaging the opposite ends of the nozzles, and means for disconnecting said arms from one nozzle or sets of nozzles at the end of a cycle of movement of the nozzle or nozales and switching them to a position to engage the nozzle or nozzles in the next plate space, as said shaft is transversely moved, and means associated with said shafts to move the arm or arms thereon.

1'1. A mechanism as set forth in claim 12, in which the means for moving the nozzle or nozzles includes shafts positioned on opposite sides of the plates, pinions on opposite ends of said shaft, and racksonwhichsaid pinions run to carry said shafts transversely across the plate spaces, sleeves on said shafts, forked arms carried by the sleeves for engaging the ends of said nozzles, and means including a cam on one end of each sleeve for switching said arms from one nozzle to another adiacent one at the end of a cleaning cycle of a nozzle, and means for moving the sleeves simultaneously with the transverse movement of the shafts.

18. In an air or gas cleaner of the type herein specified wherein groups of spaced imperforate plates are provided with surfaces which hold the particulate matter thereon after being attracted thereto by electrical charges applied to said plates; means for simultaneously cleaning two oppositely disposed surfaces of each group of plates, comprising an elongated vacuum cleaning nozzle for said surfaces and normally lying between the plates at one end thereof and extending substantially across the width of the plates, and means opposite ends of said nozzle for moving it over the said surfaces, and means for applying vacuum only and directly. to said nozzle at the surfaces engaged thereby.

19. An apparatus as set forth in claim 18, in which means are provided for automatically moving all the nozzles in one set of spaces arranged in tandem relation, and then the nozzles in the next adjacent set of spaces, and so on until all the surfaces have been cleaned.

20. An apparatus as set forth in claim 18, in which duplicate sets of mechanisms are provided on opposite sides of said groups of plates for simultaneously moving all the nozzles of the diflerent groups positioned in corresponding spaces, and then the nozzles in the next adjacent set of spaces, and so on until all the surfaces have been cleaned.

21. In an air or gas cleaner of the type herein specified wherein a group of spaced plates, impervious to the e of air or gas therethrough, are provided with surfaces which hold the particulate matter thereon after being attracted thereto by suitable electrical charges applied to said plates; means for simultaneously cleaning opposed surfaces of two adjacent plates, said means including an elongated vacuum nozzle adapted and positioned to have a suction applied to one side and provided with openings for directing a stream of air induced by the suction against the surfaces to be cleaned, and then through the nozzle into the suction passageway, when the nozzle is being moved, and means for moving the nozzle over the said surfaces.

' 22. In an apparatus as set forth in claim 21, in

which the nozzle is normally positioned at one end of the plates when they are being used to clean the air or gas, means being provided as a part of the nozzle to shut off the suction passageway.

23. In an apparatus as set forth in claim 21, in which each space between the plates is provided with a cleaning nozzle of the type described.

24. In an apparatus as set forth in claim 21, in which each space between the plates is provided with a cleaning nozzle of the type described, further means being provided to automatically move the nozzles successively.

25. An electrostatic precipitator for removing particulate matter from a stream of gas comprising; a multiplicity of imperforate collecting electrodes whereon the said matter is precipitated and held, a multiplicity of vacuum cleaner nozzles in length approximately the width of the electrode to be cleaned, means for only applying directly to and throughout the length of said nozzles and at the surfaces engaged thereby, an operating vacuum, and means for moving said nozzles over the collecting surfaces of said electrodes.

26. An electrostatic precipitator for removing particulate matter from a stream of gas comprising; a frame holding a multiplicity of collecting electrodes whereon said particulate matter is collected and held, said frame providing passageway over and between said electrodes for the passage of the gas to be cleaned, and said frame further providing passageway for a secondary stream of gas, means for so directing said secondary stream that it will effectively remove the accumulated matter on said electrodes when the energizing charge is cut off from said electrodes.

27. A device for cleaning the collecting electrodes of an electrostatic precipitator comprising; a multiplicity of vacuum cleaner nozzles, at least one passageway built into the frame of said precipitator, said passageway communicating with the several nozzles, means for moving at least one of said nozzles at a time over that part of the surface it is designed to clean, and then progressively moving each of the rest of said nozzles until the entire machine is cleaned, and means for preventing the cleaning gas from flowing through such of said nozzles as are not being used at any given instant.

28. A machine for electrostatically precipitating the particulate matter from a stream of gas and subsequently discharging said precipitated matter after collection in a secondary stream of gas. said machine being comprised of a multiplicity of identical and interchangeable units mounted in a suitable frame, said frame in association with said units providing suitable passageways for said secondary stream, and means to cause said secondary stream to pick up said precipitated matter from those parts where it has been collected.

29. An electrostatic precipitator for cleaning a gas wherein a group of spaced parallel plates are provided with surfaces which hold the particulate matter thereon when attracted thereto by electric charges applied to said plates; apparatus for cleaning said plates including a. plurality of members positioned to form a chamber extending adjacent said plates and at right angles to the plane of said plates, means for applying suction to said chamber, said chamber having openings into the several spaces between said plates, a cleaning nozzle between each pair of plates, said nozzle being normally seated so as to close said openings between said suction chamber and said plates, means to cause the flow of a cleaning gas, drawn by said suction, through such nozzles as may be off their seats as mentioned above, and means for automatically moving groups of at least one nozzle from its seat, over the surfaces of the plates with which it is associated, and back to its seat again, then successively and automatically moving other groups until the whole machine is cleaned.

30. Means for cleaning the facing surfaces of two parallel spaced plate-like electrodes of an electrostatic precipitator which consists of, a vacuum cleaner nozzle adapted to slide between said surfaces, a part of each nozzle sliding over opposite surfaces, curtain-like strips sealing the open spaces between the edges of said plates at right angles to the axis of said nozzle and between said nozzle and one of the parallel edges of said plates, and means to draw a partial vacuum in the cham ber formed between the nozzle, the plates and the curtains, said curtains being adapted to slide with said nozzle as it is moved over the said surfaces to be cleaned.

31. A unit for an electrostatic precipitator comprising a group of parallel spaced plates on which particulatematter is caught and held when properly charged, said-unit being characterized by having the various plates provided with connectors adapted to convey the charge from the several plates to the plates of a similar unit properly placed adjacent it, and further characterized in that a plurality of members are positioned with respect to said plates so as to provide a chamber for operation of a suitable vacuum cleaning device, said chamber matching with and becoming effectively continuous with a similar chamber in another identical unit, when said other unit is properly placed adjacent to it.

32. A frame fora group of units of an electrostatic precipitator, groups of which units have inter-connecting chambers for operation of an automatic vacuum cleaning device, said frame serving to connect said chambers between said interconnecting groups in order that when a source of vacuum is connected to any portion of any one of said chambers, the suction therein produced will be transmitted to each and all of said chambers.

33. An electrostatic precipitator having plates adapted to be cleaned by vacuum cleaner nozzles, and also having a frame as set forth in claim 32, further characterized in that said frame serves to carry operating mechanism to operate said vacuum cleaner nozzles.

34. An electrostatic precipitator as set forth in claim 31, in which means are provided whereby all electrode plates in the same plane becomeelectrically connected when another similar unit is properly placed adjacent to it.

35. In an electrostatic precipitator composed of a multiplicity of units each including a plurality of plates, frame sections including a top section for holding said units together, said top section having parts carrying devices serving to electrically connect together all the positive plates of the unit or units adjacent said top section, also carrying devices serving to electrically connect together all the negative plates of the same unit or units, and means associated with the plates of the various units for extending these respective electrical connections throughout the entire machine. whereby an electrical charge applied to any pair of positive or negative plates, will properly charge all the plates in the precipitator.

36. In an electrostatic precipitator composed of a piurality of units each composed of a plurality of plates having surfaces which will respond to an electrical charge to attract particulate matter thereto, means including members of a frame for holding-said units together, one of said members carrying devices serving to electrically connect together all of the positive plates of a unit. and also carrying devices serving to electrically connect together all of the negative plates of the same unit, and means associated with the different units to extend these electrical connections to all units, whereby an electric charge applied to any pair of positive or negative plates, will properly charge all of the plates.

37. An electrostatic precipitator comprising a multiplicity of identical and interchangeable units each composed of a plurality of imperforate plates, each of said units being equipped with at least one vacuum cleaner nozzle, a frame for holding said units, and means carried by the frame for successively operating groups of at least one of said vacuum cleaner nozzles at a time, and then operating successively the remaining groups until the entire machine is cleaned.

38'; An air or gas cleaner of the type herein specified, wherein a plurality of groups of spaced plates are provided with surfaces for holding particulate matter thereon after the same has been attracted thereto by electrical charges applied to said plates; elongated cleaning nozzles positioned between said spaced plates, forked members for engaging opposite ends of said nozzles, means for actuating the forked members to move the nozzles over said plates, said forked members being hollow and provided with means for completing a passageway to the nozzles with which said forked members are engaged, and means for drawing a vacuum on said nozzles through said hollow forked members.

39. An apparatus as set forth in claim 33,in which mechanism is provided for shifting said hollow members from one nozzle to an adjacent nozzle in the same horizontal group of plates and so on until all the plates. of this group have been cleaned.

40. An apparatus as set forth in claim 33, in which a plurality of pairs of said hollow members are arranged to serve, simultaneously, groups of plates in different horizontal planes.

41. An electrostatic precipitator as set forth in claim 25, in which each of said nozzles includes two oppositely-disposed elongated parts to engage and rub over the surfaces to be cleaned, an airspliting portion between said two parts, each of said two parts having a slot extending from said air-splitting portion and opening below said engaging parts toward the surfaces to be cleaned, whereby streams of air are directed against the surfaces to be cleaned as the air is moved through the nozzle by the suction in said suction passageway.

42. Means for cleaning the facing surfaces of two parallel-spaced plate-like electrodes of an electrostatic precipitator as set forth in claim 30.

in which each nozzle includes an elongated strip 3 having an opening in at least one side thereof leading to a vacuum passageway, said strip having oppositely-disposed side openings toward the surfaces to be cleaned, said strip also having air openings leading into said side openings at an 1 angle whereby air being drawn through the nozzle is caused to strike the surfaces to be cleaned before going into the vacuum passageway.

43. Means for cleaning an electrostatic precipitator'as set forth in claim 37, in which said cleaner nozzle hasoppositely-disposed parts to simultaneously engage the opposed surfaces of two adjacent plat-es, said nozzle having elongated openings therein adjacent said parts so as to direct streams of air. induced by suction in a suction passageway, against the surfaces to be cleaned. RICHARD C. THQMPSON. 

